Re: Use of installer's interactive shells on tty1-tty4
On Mon, 14 Sep 2020 at 04:05, Felix Miata <mrmazda@earthlink.net> wrote:
> Richard Owlett composed on 2020-09-13 05:15 (UTC-0500):
> > Where can I find description of using installer's interactive shells on
> > tty1-tty4?
> 1,3,4 are not available shells.
> IIRC:
That does not match my recent experience.
To explore and confirm and maybe learn something from
smarter people, I report below some actual test results:
I begin by booting the buster installer on real hardware,
and it stops at "Debian installer main menu".
Pressing alt-F2 or alt-F3 produces a prompt
"Please press Enter to activate this console."
and pressing Enter starts BusyBox.
Pressing alt-F4 displays logs.
Pressing alt-F5 or any higher F-key does nothing.
Pressing alt-F1 returns to the installer.
BusyBox 'tty' command confirms /dev/tty2 and /dev/tty3.
'echo foo >/dev/tty4' confirms that the log display is
/dev/tty4 when the string 'foo' appears there.
I was unable to find any evidence for the use of /dev/tty1,
apart from pressing alt-F1 working as expected.
But I was just poking around cluelessly for curiosity, someone
else might know a way to do that. BusyBox 'ps' appears to not
provide tty information.
In BusyBox, 'ls -R' appears unsupported, so I ran:
find /proc -type d -exec ls -l '{}' \; 2>/dev/null | grep tty1
it gave no output.
I looked at the other active processes using the same methods
without discovering anything else about /dev/tty1.
The installer PID was 257.
ls -l /proc/257/fd/
shows
2 -> /dev/tty0
BusyBox 'echo' to /dev/tty0 did not affect the installer screen.
However, I saw that process '/usr/bin/main-menu' used /dev/pts/0
and 'echo' to that device did write text into the installer screen.
At the "Debian installer main menu" I activated the
"Execute a shell" menu entry. In this shell
$ tty
/dev/pts/0
It appears that /dev/pts/0 performs the role of /dev/tty1.
I'm not very knowledgeable about all this tty stuff so I will leave
it at that.
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